1、 Standard Method of Test for Asphalt Binder Content of Asphalt Mixtures by the Nuclear Method AASHTO Designation: T 287-14 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2c T 287-1 AASHTO Standard Method of Test f
2、or Asphalt Binder Content of Asphalt Mixtures by the Nuclear Method AASHTO Designation: T 287-14 1. SCOPE 1.1. This procedure covers the quantitative determination of the asphalt binder content of asphalt mixtures by testing a sample with a nuclear gauge that utilizes neutron-thermalization techniqu
3、es. 1.2. The values expressed in SI units are to be regarded as the standard. The inch-pound equivalents of the SI units may be approximate. 1.3. Nuclear gauge operations and maintenance are not covered in detail. See the manufacturers manual for details. 1.4. This test method involves potentially h
4、azardous materials, operations, and equipment. This method does not purport to address all of the safety concerns associated with its use. All operators will be trained in radiation safety prior to operating nuclear gauges. Some agencies require the use of personal monitoring devices such as a therm
5、oluminescent dosimeter or film badge. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 231, Weighing Devices Used in the Testing of Materials R 66, Sampling Asphalt Materials T 2, Sampling of Aggregates T 11, Materials Finer Than 75-m (No. 200) Sieve in Mineral Aggregates by Washing T 27, Sieve Anal
6、ysis of Fine and Coarse Aggregates T 110, Moisture or Volatile Distillates in Hot Mix Asphalt (HMA) T 168, Sampling Bituminous Paving Mixtures T 248, Reducing Samples of Aggregate to Testing Size T 255, Total Evaporable Moisture Content of Aggregate by Drying T 329, Moisture Content of Asphalt Mixtu
7、res by Oven Method 3. SUMMARY OF METHOD 3.1. This procedure can be used for rapid determination of the asphalt binder content of asphalt mixtures. It is suitable for quality control and acceptance testing for construction and for research and development applications. This procedure is useful in the
8、 determination of asphalt binder content only and does not provide for gradation analysis. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 287-2 AASHTO 3.2. This procedure determines the asphalt
9、binder content of a test sample by comparing the measured asphalt binder content with previously established calibration data. The asphalt binder content is expressed as a percentage of the mass of the asphalt mixture. 3.3. Accurate results are dependent upon proper calibration of the nuclear gauge
10、to the material being tested as covered in Annex A. This procedure is sensitive to the type and gradation of the aggregate, liquid anti-stripping additive or hydrated lime, and the percentage and source of the asphalt binder. 3.4. This procedure measures the total amount of hydrogen in a sample incl
11、uding the hydrogen present in the form of water. Unless the test sample is totally free of water, the moisture content must be determined according to T 110 or T 329 and the percentage subtracted from the asphalt binder content measured by the nuclear gauge. Alternatively, prior to testing, the samp
12、le may be dried to a constant mass in accordance with T 329, thereby nullifying the need for a moisture correction. 3.5. This procedure can be used with recycled asphalt pavement (RAP) incorporated into the asphalt mixture, provided that the RAP is of uniform gradation, asphalt binder content, and a
13、sphalt binder type. When RAP is used, the RAP should be mixed in the calibration samples in the same proportion that will be used on the construction project. 4. APPARATUS 4.1. Nuclear asphalt binder content gauge system consisting of: 4.1.1. Neutron Sourcean encapsulated and sealed radioactive sour
14、ce; 4.1.2. Thermal neutron detectors; 4.1.3. Readout instrumentdisplaying, at a minimum, the percent of asphalt binder to the nearest 0.1 percent; and 4.1.4. Three or more stainless-steel sample pansconforming to the gauge requirements. 4.2. Mechanical mixer with a 10-kg (22-lb) capacity, capable of
15、 producing a completely mixed, well- coated, homogeneous asphalt mixture. 4.3. Sample containers such as paint cans or unwaxed, nonabsorbent cardboard boxes that can be closed to prevent contamination of the sample and are capable of withstanding the heating of the asphalt mixture to the mixing temp
16、erature. 4.4. Sample-quartering apparatus conforming to the requirements of T 248, Method B. 4.5. General-purpose balance or scale conforming to M 231, 20-kg (44-lb) capacity, readable to 0.1 g. 4.6. Drying Ovencapable of handling the required number of samples and sample sizes, of either of the fol
17、lowing types: 4.6.1. Forced-air convection oven capable of maintaining a temperature of 177 3C (350 5F). 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 287-3 AASHTO 4.6.2. Microwave oven, determ
18、ined not to be detrimental to the aggregate, capable of maintaining a temperature of 177 3C (350 5F). 4.7. Leveling Plateflat, rigid plate of metal minimum thickness of 10 mm (0.4 in.), Plexiglas minimum thickness of 12.5 mm (0.5 in.), or nonabsorptive plywood minimum thickness of 19 mm (0.75 in.),
19、slightly larger than the sample pans. 4.8. Thermometer with a temperature range of 10 to 260C (50 to 500F). 4.9. Assorted pans, spoons, spatulas, and mixing bowls. 4.10. Radioactive materials information/calibration packet containing: 4.10.1. Daily standard count log; 4.10.2. Factory/laboratory cali
20、bration data sheet; 4.10.3. Leak test certificate; 4.10.4. Shippers declaration for dangerous goods; 4.10.5. Procedure memo for storing, transporting, and handling nuclear testing equipment; and 4.10.6. Other radioactive materials documentation conforming to local regulatory requirements. 5. PRECAUT
21、IONS 5.1. The nuclear asphalt binder content gauge may be sensitive to outside influences and therefore: 5.1.1. Any other source of neutron radiation shall be kept at least 10 m (33 ft) from the apparatus during use; 5.1.2. The space within 1 m (3.3 ft) of the apparatus shall be kept free of hydroge
22、nous material such as water, plastics, asphalt binder, or asphalt mixtures during use; 5.1.3. All personnel shall be kept at least 1 m (3.3 ft) away from the gauge during testing; and 5.1.4. The gauge shall not be located within 10 m (33 ft) of any water supply tanks, fuel tanks, or other liquid con
23、tainers subject to fluctuating liquid levels. 5.2. Moving the apparatus to a different location, even within the same laboratory, may cause a change in the background radiation measurements. New background measurements, and possibly recalibration, will be necessary prior to use whenever background c
24、onditions have changed. See Sections 6 and 7 for instructions concerning calibration and background measurements. 6. CALIBRATION 6.1. Perform calibrations and cross-calibrations on asphalt mixtures tested in gauges, and transfer calibrations between gauges according to Annex A. 2015 by the American
25、Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 287-4 AASHTO 7. STANDARDIZATION 7.1. Obtain and record a background count in accordance with the manufacturers procedure each day prior to taking test measurements or w
26、henever the gauge has been moved or the conditions within 1 m (3.3 ft) of the gauge have changed. The measurement time for the background count should be the same as that used for the test measurements. 7.2. If the background count has not changed by more than 1 percent from the previous background
27、count, then the apparatus shall be considered stable and acceptable for use. If the gauge has been moved or if the surrounding conditions have changed, additional background counts must be obtained until the 1 percent standard is satisfied. 8. PROCEDURE 8.1. Obtain a representative sample of asphalt
28、 mixture in accordance with T 168. If required, reduce the sample to the approximate test size by splitting or quartering according to T 248, Method B. It is recommended that testing be performed while the asphalt mixture is still hot, and not reheated, if possible. If the asphalt mixture cools and
29、reheating is necessary, heat it to the midpoint of the compaction temperature range for the asphalt binder used in the asphalt mixture. 8.2. Determine the mass of a clean gauge-sample pan, and tare the pan on the scale. 8.3. Place the asphalt mixture into the pan until it is about half full. Lightly
30、 tamp the asphalt mixture in the pan with a preheated spoon or spatula. 8.4. Place additional asphalt mixture into the pan until the required mass, as determined in Annex A, is reached within 5 g. 8.5. Place the leveling plate on top of the asphalt mixture immediately after filling the pan. Compact
31、the sample into the pan until it is level with the top of the pan by pressing down on the plate. Sight across the top of the pan to ensure that the asphalt mixture does not protrude above the pan. 8.6. Record the mass of the asphalt mixture compacted into the pan. The mass shall be within 5 g of the
32、 target mass. Note 1If the gauge does not have temperature-compensation capability, measure and record the temperature of the compacted specimen. This temperature must be within 5C (9F) of the calibration-test-specimen temperature. 8.7. If the gauge has the ability to store multiple calibrations, ac
33、tivate the calibration for the particular asphalt mixture. Place the pan into the gauge, and perform a 4-min count. 8.8. Determine the uncorrected asphalt binder content by direct readout from the gauge, calibration graph, or formula supplied by the manufacturer. Record the uncorrected asphalt binde
34、r content from the 4-min reading to the nearest 0.1 percent. 8.9. Using a representative portion of the original sample or a portion of the material removed from the gauge pan, determine the moisture in the asphalt mixture according to T 110 or T 329, and record it to the nearest 0.1 percent. Altern
35、atively, prior to testing, the sample may be dried to a constant mass in accordance with T 329, thereby nullifying the need for a moisture correction. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2
36、c T 287-5 AASHTO 9. CALCULATION 9.1. When determined, subtract the moisture content from the uncorrected asphalt binder content. Record this value as the corrected asphalt binder content. 10. REPORT 10.1. Report the following information: 10.1.1. Make, model, and serial number of the nuclear asphalt
37、 binder content gauge; 10.1.2. Date and source of the calibration; 10.1.3. Date of the test; 10.1.4. Name and signature of the operator; 10.1.5. Background count for the day of the test; 10.1.6. Asphalt mixture identification; 10.1.7. Aggregate type and sources; 10.1.8. Asphalt binder grade and sour
38、ce; 10.1.9. When used, source and amount of liquid anti-stripping additive or hydrated lime; 10.1.10. Calibration sample mass and temperature; 10.1.11. Test-sample mass and temperature if the gauge does not have temperature-compensation capability; 10.1.12. Gauge reading; and 10.1.13. Corrected asph
39、alt binder content value to the nearest 0.1 percent. ANNEXES (Mandatory Information) A1. SCOPE A1.1. This annex covers the preparation of samples for, and the calibration of, nuclear asphalt binder content gauges. Job-mix formula (JMF) calibration and cross-calibration of master and field gauges are
40、 included. A2. SAMPLING A2.1. Obtain samples of aggregate according to T 2. Approximately 50 kg (110 lb) will be required for the calibration specimens. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS
41、-2c T 287-6 AASHTO A2.2. Obtain samples of asphalt binder according to R 66. Approximately 4 L (1 gal) will be required. Note A1The more accurately the ingredient materials (including liquid anti-stripping additive or hydrated lime) are prepared to match the JMF, the closer the calibration points wi
42、ll be to the production asphalt mixture; and, therefore, the more accurate the results will be. A3. AGGREGATE PREPARATION A3.1. When used, hydrate the appropriate amount of lime on the aggregate. A3.2. Dry the aggregate to a constant mass in accordance with T 255. A3.3. Separate the aggregate blend
43、by dry-sieving on the specified sieves, including the minus 75-m (No. 200) material. A3.4. Calculate the required cumulative mass for each specified sieve using the following formula: (100 )100TPX= (A3.1) where: X = the required, cumulative batch mass for each specified sieve (g); T = the initial, t
44、otal aggregate mass (g); and P = the percent passing for each specified sieve according to the JMF. A3.5. Perform an aggregate dust correction as follows: A3.5.1. Prepare a washed-gradation sample from the masses calculated in Section A3.4. A3.5.2. Perform a washed gradation according to T 27 and T
45、11. A3.5.3. Calculate the corrected batch mass for each specified sieve for the calibration points using the following formula: 2nXZY= (A3.2) where: Zn = the adjusted, cumulative batch mass for any sieve size, n (g); X = the prewash, cumulative batch mass for each specified sieve (g); and Y = the po
46、stwash, cumulative batch mass for each specified sieve (g). A3.6. Blend the aggregate together at the proper proportion to match the JMF using the masses calculated in Section A3.5.3. A4. ASPHALT BINDER PREPARATION A4.1. Heat a minimum of 2 L (0.5 gal) of asphalt binder to the midpoint of the mixing
47、 temperature range in a covered container(s). When used, add the appropriate amount of liquid anti-stripping additive to the asphalt binder. Use the asphalt binder as soon as it reaches the midpoint of the mixing temperature range. If this operation is not possible, maintain the asphalt binder at th
48、is temperature for no more than 4 h. Do not cool and reheat the asphalt binder. A4.2. Method AAsphalt binder percent by mass of the asphalt mixture. A4.2.1. Calculate the mass of asphalt binder for each calibration point as follows: 2015 by the American Association of State Highway and Transportatio
49、n Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 287-7 AASHTO B = (E)(Pbm) (A4.1) where: B = the mass of the asphalt binder to the nearest 0.1 g; E = the mass of the asphalt mixture (g); and Pbm= the percent of asphalt binder by total mass of the asphalt mixture, expressed as a decimal. Asphalt binder contents will be chosen at the optimum asphalt binder content and at increments of 0.8 percent from the optimum asphalt binder content. The minimum four samples are at 0.8 percent below op
